The Thin Blue Line

It is the tenth anniversary of Fowler and Dawkins' relationship, but Fowler manages to forget, being instead more concerned with the Queen's Official Birthday.

Habib falls for a fireman named Gary, much to Goody's jealousy, while Fowler finds himself pestered frequently by a man who claims to have committed impossible, solved or extremely historical crimes, much to DI Grim's amusement, until a terrorist begins making threats that cause Special Branch to become involved.

After Fowler drunkenly admits to having kissed Habib during a pub quiz match, Dawkins begins to suspect the two of having an affair behind her back when Grim enlists Fowler and Habib's help in catching a criminal via entrapment.